The present invention relates to urethanes.
Polyurethanes are polymers which have a high degree of strength, hardness, and friction resistance. They are used as adhesives, cements, and coatings.
Polyurethanes are polymeric compounds which contain repeating urethane groups: ##STR1##
In the past, polyurethanes have generally been made from di-isocyanates, which are highly toxic, non-stable, and react with water, such as moisture in the air. The solvents which have been used to dissolve the known polyurethanes are organic solvents, such as acetone, dioxane, and sometimes benzene, which are very volatile and which become air pollutants as they evaporate.
Some reactions are known for producing polyurethanes without the use of di-isocyanates, by reacting cyclocarbonate groups with amines, but these reactions have had the problem that they have not completely polymerized or hardened. It is said that the reaction has a tendency to "stick", meaning that it stops reacting before the polymerization is complete.